[mkgmap-dev] Inter-tile routing now available in trunk

Thu Feb 19 11:19:29 GMT 2009

On Feb 19, 2009, at 11:57, Clinton Gladstone wrote:
>> I appears to work fairly well in mapsource although I have found  
>> that for
>> long routes it gives up and draws a straight line even though it  
>> can route OK
>> if you add some intervening waypoints.
>
> I can also confirm this behaviour: in a test crossing multiple tiles
> over a long distance (from Heilbronn to Cologne), Mapsource attempted
> several recalculations and then drew a straight line from start to
> destination. When I added an additional point to the route, Mapsource
> immediately recalculated the route correctly.

If you shift this additional point towards the destination, is there a  
specific point where it starts going wrong?

One possibility is that the routes are just getting too long. I  
remember somebody saying there's a limit on the number of legs when  
routing using Garmin units.

This might be fixed by writing so-called links (shortcuts in the  
routing graph), which we're not doing at all at the moment.  
Unfortunately, they're less well understood.

If there's a problem routing from Heilbronn to Cologne, it'd be  
interesting to see if that also shows up within a single tile. Say, a  
tile with all of Heilbronn and Cologne, but only motorways in between.

Cheers
Robert